My samsung s4 won't turn on ?

Hello,so I got this phone in August (second handed) and the battery was crappy ,1 % drained in one minute or even 40 seconds ,the phone would discharge in 1 hour and a half so I got another battery (not an original one) .
A week ago it started randomly going off and then I would have trouble turning it back on, I had to take the battery out and put it back on like 5 times to get it to work again. The logo would come on for 2 seconds and then it would turn off again.After a couple of days it wouldn't work at all , so I thought I should try the old battery but it wouldn't work either. I tried resetting the phone but after I would press the home,power and volume up keys to reset it the menu would appear for 2 seconds and then the phone goes out again. I tried another charger also, still the same.
Yesterday I charged it again and amazingly the phone turned on ,just for a couple of hours,when I tried to use it after a while ,it died again. when i charge it the phone gets warm so I have no idea what could be wrong.
Should I get a new battery or should I go to the service and let the people there tell me whats wrong?